Merged a customer in Shopify, still two people in Klaviyo
You merge two duplicate customers in Shopify, and a week later Klaviyo is still emailing both of them. Shopify does announce every merge to connected apps — the gap is that nothing on the Klaviyo side is documented to act on it. Here is why that happens, how to clear it up by hand, and the trap that can undo the clean-up.
A merchant who merged two customers in Shopify reported that nothing changed in Klaviyo, and others have asked since whether that has moved. Both profiles stay there, both keep receiving your flows, and the customer you just tidied up gets every campaign twice.
It is not that Shopify keeps the merge to itself. Shopify announces every merge to any app that asks to hear it — there is a dedicated event for it, "Triggers when two customers are merged", naming which profile was kept and which was deleted. The gap is on the receiving side: Klaviyo's Shopify integration does not document doing anything with that event, and merchants who have asked have not had an answer.
What is and is not documented
Worth being precise here, because most of what you will read overstates it.
Shopify documents its half. The merge event exists and carries both profile IDs.
Klaviyo documents nothing on its side. Its guide to the Shopify integration does not mention merges at all. The sentence you will find quoted everywhere — "When a customer profile is merged in Shopify, the changes are not propagated to Klaviyo" — comes from a merchant's post on Klaviyo's community in October 2023, in a thread asking Klaviyo to build exactly this. No one from Klaviyo replied, and the follow-ups asking whether it had shipped were still unanswered in 2025.
So the honest statement is that Klaviyo does not document syncing merges, and merchants report that it does not. Plan on it not happening.
Klaviyo does merge profiles on its own — but only when one action ties an email to a phone number or a device. Two profiles with two different email addresses, which is what a Shopify duplicate almost always is, never trip that.
Merged customers still getting two of everything? Describe how your merges should reach Klaviyo →
Merging the Klaviyo side by hand
Klaviyo has its own merge, and it is quick: open the profile, "select Merge Profile under Profile actions", choose the duplicate, confirm. Three things about how it behaves, all from Klaviyo's own help:
It is permanent. "This action is permanent."
The kept profile wins any disagreement. Details on the profile you remove are carried across "only when they do not already exist on the remaining profile" — so pick the profile you keep for the details you trust. Event history, on the other hand, comes across in full.
Suppression is contagious. "If you merge a suppressed profile with an active profile, the resulting profile will be suppressed by default." Merge a profile that once unsubscribed into an active one, and you have unsubscribed the active one.
And the trap that undoes the work. Klaviyo's own FAQ: "If a source profile is merged into a destination profile, and Klaviyo then receives another event with the email address from the original source profile, a new profile is created with that email address." If the old email is still anywhere in Shopify — on an old order, on the profile you did not merge on the Shopify side — Klaviyo can quietly create the duplicate again. Merge in Shopify first, then in Klaviyo — that removes the most common source of the old address, though an old order can still carry it.
Which route is yours
| What you need | Where it comes from |
|---|---|
| Merge two customers in Shopify | Native — the admin merge |
| The same merge to reach Klaviyo | Not documented by Klaviyo — do it by hand, or build the relay |
| Merge two profiles in Klaviyo | Native in Klaviyo — Profile actions → Merge Profile |
| Keep a merge from coming undone | Merge in Shopify first — it removes the most common source |
| Merge a profile that once unsubscribed | Possible — but the result is suppressed by default |
What Shopivibe does
For a handful of merges, do both sides by hand, Shopify first. It takes a minute each.
Where this becomes worth asking for is when merging is routine: "every time I merge two customers in Shopify, merge the same two in Klaviyo, keeping the profile Shopify kept." Shopify already sends the event that makes this possible, and Klaviyo has an API that accepts it. What is missing is the relay between them, and that is a build.
Two things to say plainly. The relay is built for you, not switched on — Shopify's merge event and Klaviyo's merge API are both there, and a person here connects them for your store. And the suppression rule still applies to anything we merge on your behalf, because it is Klaviyo's rule, not ours. A person here takes it on straight away and has it working in your store within 24 hours.
Shopivibe solves the problem in your store and keeps what it adds maintained, including when Shopify changes something underneath. Shopivibe is free during early access, with 3,500 credits included. Credits beyond the included 3,500 cost $0.06 each.
Merging customers often enough that Klaviyo should follow? Describe it in your own words →
Checked against Shopify's documentation and the App Store on 22 September 2026.